Introduction to Genetics
Genetics Is Important to Us Individually, to Society, and to the Study of Biology
Humans Have Been Using Genetics for Thousands of Years
A Few Fundamental Concepts Are Important for the Start of Our Journey into Genetics
Chromosomes and Cellular Reproduction
Prokaryotic and Eukaryotic Cells Differ in a Number of Genetic Characteristics
Cell Reproduction Requires the Copying of the Genetic Material, Separation of the Copies, and Cell Division
Sexual Reproduction Produces Genetic Variation Through the Process of Meiosis
Basic Principles of Heredity
Gregor Mendel Discovered the Basic Principles of Heredity
Monohybrid Crosses Reveal the Principle of Segregation and the Concept of
Dihybrid Crosses Reveal the Principle of Independent Assortment
Observed Ratios of Progeny May Deviate from Expected Ratios by Chance
Sex Determination and Sex-Linked Characteristics
Sex Is Determined by a Number of Different Mechanisms
Sex-linked Characteristics Are Determined by Genes on the Sex Chromosomes
Dosage Compensation Equalizes the Amount of Protein Produced by X-Linked Genes in Males and Females
Extensions and Modifications of Basic Principles
Additional Factors at a Single Locus Can Affect the Results of Genetic Crosses
Gene Interaction Takes Place When Genes at Multiple Loci Determine a Single Phenotype
Sex Influences the Inheritance and Expression of Genes in a Variety of Ways
Anticipation Is the Stronger or Earlier Expression of Traits in Succeeding Generations
The Expression of a Genotype May Be Affected by Environmental Effects
Pedigree Analysis, Applications, and Genetic Testing
The Study of Genetics in Humans Is Constrained by Special Features of Human Biology and Culture
Geneticists Often Use Pedigrees to Study the Inheritance of Characteristics in Humans
Studying Twins and Adoptions Can Help Assess the Importance of Genes and Environment
Genetic Counseling and Genetic Testing Provide Information to Those Concerned about Genetic Diseases and Traits
Comparison of Human and Chimpanzee Genomes Is Helping to Reveal Genes That Make Humans Unique
Quantitative Genetics
Quantitative Characteristics Vary Continuously and Many Are Influenced by Alleles at Multiple Loci
Statistical Methods Are Required for Analyzing Quantitative Characteristics
Heritability Is Used to Estimate the Proportion of Variation in a Trait That Is Genetic
Genetically Variable Traits Change in Response to Selection
Linkage, Recombination, and Eukaryotic Gene Mapping
Linked Genes Do Not Assort Independently
Linked Genes Segregate Together and Crossing Over Produces Recombination Between Them
A Three-Point Testcross Can Be Used to Map Three Linked Genes
Physical-Mapping Methods Are Used to Determine the Physical Positions of Genes on Particular Chromosomes
Recombination Rates Exhibit Extensive Variation
Bacterial and Viral Genetic Systems
Genetic Analysis of Bacteria Requires Special Methods
Bacteria Exchange Genes Through Conjugation, Transformation, and Transduction
Viruses Are Simple Replicating Systems Amenable to Genetic Analysis
Chromosome Variation
Chromosome Mutations Include Rearrangements, Aneuploids, and Polyploids
Chromosome Rearrangements Alter Chromosome Structure
Aneuploidy Is an Increase or Decrease in the Number of Individual Chromosomes
Polyploidy Is the Presence of More Than Two Sets of Chromosomes
Chromosome Variation Plays an Important Role in Evolution
DNA: The Chemical Nature of the Gene
Genetic Material Possesses Several Key Characteristics
All Genetic Information Is Encoded in the Structure of DNA or RNA
DNA Consists of Two Complementary and Antiparallel Nucleotide Strands That Form a Double Helix
Special Structures Can Form in DNA and RNA
Chromosome Structure and Transposable Elements
Large Amounts of DNA Are Packed into a Cell
Eukaryotic Chromosomes Possess Centromeres and Telomeres
Eukaryotic DNA Contains Several Classes of Sequence Variation
Transposable Elements Are DNA Sequences Capable of Moving
Different Types of Transposable Elements Have Characteristic Structures
Transposable Elements Have Played an Important Role in Genome Evolution
DNA Replication and Recombination
Genetic Information Must Be Accurately Copied Every Time a Cell Divides
All DNA Replication Takes Place in a Semiconservative Manner
Bacterial Replication Requires a Large Number of Enzymes and Proteins
Eukaryotic DNA Replication Is Similar to Bacterial Replication but Differs in Several Aspects
Recombination Takes Place Through the Breakage, Alignment, and Repair of DNA Strands
Transcription
RNA, Consisting of a Single Strand of Ribonucleotides, Participates in a Variety of Cellular Functions
Transcription Is the Synthesis of an RNA Molecule from a DNA Template
The Process of Bacterial Transcription Consists of Initiation, Elongation, and Termination
Eukaryotic Transcription Is Similar to Bacterial Transcription but Has Some Important Differences
Transcription in Archaea Is More Similar to Transcription in Eukaryotes Than to Transcription in Eubacteria
RNA Molecules and RNA Processing
Many Genes Have Complex Structures
Messenger RNAs, Which Encode the Amino Acid Sequences of Proteins, Are Modified after Transcription in Eukaryotes
Transfer RNAs, Which Attach to Amino Acids, Are Modified after Transcription in Bacterial and Eukaryotic Cells
Ribosomal RNA, a Component of the Ribosome, Also Is Processed after Transcription
Small RNA Molecules Participate in a Variety of Functions
The Genetic Code and Translation
Many Genes Encode Proteins
The Genetic Code Determines How the Nucleotide Sequence Specifies the Amino Acid Sequence of a Protein
Amino Acids Are Assembled into a Protein Through the Mechanism of Translation
Additional Properties of RNA and Ribosomes Affect Protein Synthesis
Control of Gene Expression in Prokaryotes
The Regulation of Gene Expression Is Critical for All Organisms
Operons Control Transcription in Bacterial Cells
Some Operons Regulate Transcription Through Attenuation, the Premature Termination of Transcription
RNA Molecules Control the Expression of Some Bacterial Genes
Control of Gene Expression in Eukaryotes
Eukaryotic Cells and Bacteria Have Many Features of Gene Regulation in Common, but They Differ in Several Important Ways
Changes in Chromatin Structure Affect the Expression of Genes
Epigenetic Effects Often Result from Alterations in Chromatin Structure
The Initiation of Transcription Is Regulated by Transcription Factors and Transcriptional Regulator Proteins
Some Genes Are Regulated by RNA Processing and Degradation
RNA Interference Is an Important Mechanism of Gene Regulation
Some Genes Are Regulated by Processes That Affect Translation or by Modifications of Proteins
Gene Mutations and DNA Repair
Mutations Are Inherited Alterations in the DNA Sequence
Mutations Are Potentially Caused by a Number of Different Natural and Unnatural Factors
Mutations Are the Focus of Intense Study by Geneticists
A Number of Pathways Repair Changes in DNA
Molecular Genetic Analysis and Biotechnology
Techniques of Molecular Genetics Have Revolutionized Biology
Molecular Techniques Are Used to Isolate, Recombine, and Amplify Genes
Molecular Techniques Can Be Used to Find Genes of Interest
DNA Sequences Can Be Determined and Analyzed
Molecular Techniques Are Increasingly Used to Analyze Gene Function
Biotechnology Harnesses the Power of Molecular Genetics
Genomics and Proteomics
Structural Genomics Determines the DNA Sequences of Entire Genomes
Functional Genomics Determines the Function of Genes by Using Genomic-Based Approaches
Comparative Genomics Studies How Genomes Evolve
Proteomics Analyzes the Complete Set of Proteins Found in a Cell
Organelle DNA
Mitochondria and Chloroplasts Are Eukaryotic Cytoplasmic Organelles
Mitochondrial DNA Varies Widely in Size and Organization
Chloroplast DNA Exhibits Many Properties of Eubacterial DNA
Through Evolutionary Time, Genetic Information Has Moved Between Nuclear, Mitochondrial, and Chloroplast Genomes
Damage to Mitochondrial DNA Is Associated with Aging
Developmental Genetics and Immunogenetics
Development Takes Place Through Cell Determination
Pattern Formation in Drosophila Serves As a Model for the Genetic Control of Development
Genes Control the Development of Flowers in Plants
Programmed Cell Death Is an Integral Part of Development
The Study of Development Reveals Patterns and Processes of Evolution
The Development of Immunity Is Through Genetic Rearrangement
Cancer Genetics
Cancer Is a Group of Diseases Characterized by Cell Proliferation
Mutations in a Number of Different Types of Genes Contribute to Cancer
Changes in Chromosome Number and Structure Are Often Associated with Cancer
Viruses Are Associated with Some Cancers
Epigenetic Changes Are Often Associated with Cancer
Colorectal Cancer Arises Through the Sequential Mutation of a Number of Genes
Population Genetics
Genotypic and Allelic Frequencies Are Used to Describe the Gene Pool of a Population
The Hardy–Weinberg Law Describes the Effect of Reproduction on Genotypic and Allelic Frequencies
Nonrandom Mating Affects the Genotypic Frequencies of a Population
Several Evolutionary Forces Potentially Cause Changes in Allelic Frequencies
Evolutionary Genetics
Organisms Evolve Through Genetic Change Taking Place Within Populations
Many Natural Populations Contain High Levels of Genetic Variation
New Species Arise Through the Evolution of Reproductive Isolation
The Evolutionary History of a Group of Organisms Can Be Reconstructed by Studying Changes in Homologous Characteristics
Patterns of Evolution Are Revealed by Changes at the Molecular Level
Reference Guide to Model Genetic Organisms